The Math of Better Decisions
Like Duolingo, but for The Math of Better Decisions. Tomo turns the whole topic into a game you play five minutes a day, until it actually sticks.
For the part of you with thirty open tabs that never became anything.
A short one: 12 levels across 2 sections, about 24 minutes end to end, roughly 5 days at five minutes a day. It moves through Calculating the Odds and Navigating Complexity. It assumes you already know the basics.
Free forever · No credit card · iPhone & Android

Key ideas in The Math of Better Decisions
- Multiply each outcome's value by its decimal probability
- Sum the positive and negative results to find the average outcome
- Extreme negative outcomes can outweigh high-frequency small gains
- Mathematical 'ruin' occurs when a single loss ends the ability to play
- Calculating expected value by weighting outcomes by their probability
- Recognizing that high-probability wins can be mathematically 'bad' if the downside is ruinous
- Long shots are rational if the payout ratio exceeds the odds of losing
- Sunk costs are historical data and do not change future probabilities
- EV+ is achieved when the potential prize divided by the cost is greater than the odds
- Identifying when a massive payoff justifies a low-probability 'long shot'
- Only future incremental costs should be weighed against potential gains
- Excluding sunk costs from future-facing expected value decisions
- Convert time saved into a fraction of your hourly dollar value
- A decision is mathematically sound if the fee is less than the time-value saved
- Quantifying time-saving decisions using an hourly rate
- The Prior is the probability of a hypothesis being true before new data is seen
You've tried the other tabs
Thirty open tabs. Four facts you actually kept.
You watched. You nodded. By Sunday it was gone.
One answer, then back to scrolling.
Eight weeks. You meant to finish. You didn't.
Tomo gives The Math of Better Decisions the Duolingo treatment: levels, streaks, and quick quizzes that test what you just learned. That game loop is what the tabs above never had, so it's the one you actually finish.
Here's what playing it feels like
A real question from this course. Take your best guess.
If you have a 20% chance of winning $100, how do you mathematically represent that specific part of the gamble?
Get it right to open this lesson and 11 more in the app.
Where The Math of Better Decisions takes you
Move beyond simple arithmetic to master the mathematical frameworks that drive smart choices. Learn to calculate risk, update your beliefs with data, and navigate strategic competition.
- 1
Calculating the Odds
- Expected Value: The Price of a Choice
- Bayesian Thinking: Updating Your Worldview
- 2
Navigating Complexity
- Fat Tails and Outliers
- Game Theory: Thinking Steps Ahead
2 sections · 4 units · 12 levels. Built to play, not to enroll.
You pick the voice
The Math of Better Decisions is taught in the The Bestie style: your friend who just gets it. Want a different feel? In the app you can spin up the same topic in any of Tomo's teaching styles. Same facts, totally different vibe.
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Start The Math of Better Decisions today.
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